ASSESSMENT OF MALE ANDROGEN EXPOSURE: A SURVEY ON MEASUREMENT AND REPORTING OF TOTAL TESTOSTERONE, SEX HORMONE-BINDING GLOBULIN, AND FREE TESTOSTERONE IN CLINICAL LABORATORIES ACROSS EUROPE Free

The evaluation of male hypogonadism encompasses clinical parameters and biochemical measures of total testosterone (T), sex hormone-binding globulin (SHBG), and free T. Laboratory standardization is however lacking, leading to methodological inconsistencies between laboratories and varying reference ranges. We investigated inter-laboratory methodologic differences in total T, SHBG, and free T in clinical laboratories throughout Europe.

An internet-based, open-invitation survey was distributed from December 2022 to December 2023 by the Royal Belgian Society for Laboratory Medicine (RBSLM), the Dutch Association for Clinical Chemistry and Laboratory Medicine (NVKC), the European Academy for Andrology (EAA), the European Federation for Laboratory Medicine (EFLM), the European Society for Sexual Medicine (ESSM), and Andronet. Belgian clinical laboratories were also directly contacted by e-mail. Included in this survey on total T, SHBG, and free T were sampling, methodology, reference ranges, and reporting of results.

A total of 124 records were analyzed representing clinical laboratories from 27 European countries. These laboratories were private-sector (20.2%), research-focused (1.6%), or associated with a general (38.7%) or tertiary/university hospital (39.5%). Methodologies used for total T included enzyme-linked immunoassay (IA) (72.7%), radioimmunoassay (RIA) (1.7%), mass spectrometry (MS) (8.3%), or a combination (17.3%). While only 43.0% of respondents recommended sampling time to clinicians, even less recommended fasting (25.4%). When reporting total T (IA vs. MS), laboratories used non-stratified (20.0% vs. 16.7%) or age-stratified (79.0% vs. 70.8%) reference ranges.

For SHBG, all laboratories used IA and reported using non-stratified (34.0%) or age-stratified (65.0%) reference ranges, for which a majority provided the assay manufacturer as the source (83.1%). Free T was performed using calculation (79.3%) or measurement (10.3%) methods or a combination (10.3%). Calculation of free T was predominantly done by the Vermeulen formula (84.2%). Measurement of free T was performed (n = 10) by direct IA or RIA (60.0% and 20.0%) or MS after equilibrium dialysis or liquid–liquid extraction (20.0%).

We observed heterogeneity in measurement and reporting of total T, SHBG, and free T between clinical laboratories in Europe, highlighting the necessity of harmonization and standardization.

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